A wide variety of mechanical refrigeration systems are in use currently in a wide variety of applications. These applications include refrigerators, heat pumps, and air conditioners used both in vehicles and in buildings. The vast majority of mechanical refrigeration systems operate according to similar, well known principles, employing a closed-loop fluid circuit through which refrigerant flows. Fluorocarbon refrigerants (such as DUPONT FREON brand refrigerant) are the types of refrigerants used most widely today. DUPONT and FREON are registered trademarks of E. I. DuPont de Nemours & Company of Wilmington, Del.
Mechanical refrigeration systems periodically require servicing. This servicing often takes the form of the addition of refrigerant into the system to replace refrigerant which has escaped from the system. Other servicing often takes the form of repairs to, or replacements of components in the system such as compressors, evaporators, filters, dryers, expansion valves and condensers.
Before adding refrigerant, or repairing or replacing one or more components, it is often necessary to remove the refrigerant remaining in the system. Typically, this remaining refrigerant is removed by bleeding off the refrigerant to the atmosphere.
In recent years, much concern has arisen about this practice of releasing fluorocarbon-based refrigerants into the atmosphere. The release of such fluorocarbons is believed to deplete the concentration of ozone in the atmosphere. This ozone depletion is believed to adversely affect the environment and human health.
To avoid releasing these fluorocarbons into the atmosphere, devices have been constructed that are designed to recover the refrigerant from the refrigeration system. An example of such a refrigerant recovery device is shown in the applicants' U.S. Pat. No. 4,942,741 of Jul. 24, 1990, entitled Refrigerant recovery device. Examples of other devices are shown in Koser U.S. Pat. No. 4,285,206; Staggs et al., U.S. Pat. No. 4,539,817; Lower et al., U.S. Pat. No. 4,364,236; Lower et al., U.S. Pat. No. 4,441,330; Goddard U.S. Pat. No. 4,476,668; Manz, et al., U.S. Pat. No. 4,768,347; and Cain, U.S. Pat. No. 4,261,178.
Some of the devices described above are used solely to recover refrigerants from the mechanical refrigeration system. Others of the devices, such as the device shown in the Applicants' 741 patent are designed both to recover refrigerant from a mechanical refrigeration system, and to process that refrigerant to remove contaminants from the refrigerant.
One difficulty encountered with the removal of refrigerant from a refrigeration system is the time required to remove the refrigerant. Although removal time is not that critical when servicing a relatively small volume refrigeration system, such as the air conditioning system in a car, or a room air conditioning system, the time required to remove refrigerant from a large system can be substantial. Examples of larger mechanical refrigeration systems include commercial freezers and refrigerators, and air conditioning systems used in commercial, industrial and office buildings.
Mechanical refrigeration systems typically have a high pressure port and a low pressure port through which refrigerant can be introduced to, or removed from the system. The refrigerant in the area of the system adjacent to the high pressure port of the refrigeration system is typically in liquid form. The refrigerant adjacent to the low pressure port of the refrigeration system is typically in a gaseous state.
Most refrigerant purge systems remove the refrigerant from the refrigeration system by evacuating the refrigerant in a gaseous form from the low pressure port of the mechanical refrigeration system. It has been found by applicants that the time required to remove refrigerant from a refrigeration system is decreased substantially if the refrigerant is recovered from the system as liquid refrigerant, by removing refrigerant through the high pressure port of the mechanical refrigeration system.
Several difficulties exist with the removal of liquid refrigerant from a refrigeration system. One difficulty is that a compressor cannot be used to draw liquid refrigerant out of the system directly, by placing the compressor in the conduit between the mechanical refrigeration system and a storage tank. The flow of liquid refrigerant through a compressor will likely damage or destroy the compressor.
Another difficulty is that to remove the liquid refrigerant efficiently, pressure should be maintained on the liquid refrigerant to maintain the liquid refrigerant in a liquid state as it moves from a mechanical refrigeration system into the storage tank. If the liquid refrigerant is allowed to expand into its gaseous form, much of the time efficiencies gained by removal of the refrigerant as liquid refrigerant is lost.
It is therefore one object of the present invention to provide a device that helps to overcome these problems by an enabling a substantial portion of refrigerant in a mechanical refrigeration system to be removed in a liquid state refrigerant rather than in a gaseous state.